US11873584B2ActiveUtilityA1
Precursor stabilisation process
Est. expiryOct 10, 2037(~11.3 yrs left)· nominal 20-yr term from priority
D01F 9/225C01B 32/05C08J 5/00D01F 6/18D01F 6/40C08J 2333/20B01J 8/0285D01D 10/02B01J 8/001D01F 6/38D01F 6/54D01F 8/08D01F 11/06
60
PatentIndex Score
0
Cited by
22
References
12
Claims
Abstract
The invention relates to an improved process for forming a stabilised precursor that is suitable for the manufacture of carbon materials, such as carbon fibre. The process can convert a precursor comprising polyacrylonitrile into a stabilised precursor with greater efficiency. The invention also relates to a process for preparing a carbon fibre that utilises the stabilised precursor.
Claims
exact text as granted — not AI-modifiedThe invention claimed is:
1. A process for preparing a stabilised precursor in no more than 25 minutes, the process comprising: heating a precursor comprising polyacrylonitrile at a temperature in a range of from 250° C. to 400° C. in a substantially oxygen-free atmosphere containing not more than 0.005% by volume of an oxygen containing molecule while applying a substantially constant amount of tension that varies by less than 5% to the precursor to promote cyclisation of nitrile groups in the precursor, the temperature and time period in which the precursor is heated in the substantially oxygen-free atmosphere and the amount of tension applied to the precursor each being selected to form a pre-stabilised precursor having at least 10% cyclised nitrile groups (EOR (%)) as determined by Fourier transform infrared (FT-IR) spectroscopy using the following equation:
EOR
(
%
)
=
(
100
×
0.29
×
Abs
(
1590
)
)
(
(
Abs
(
2242
)
+
(
0.29
×
Abs
(
1590
)
)
where Abs (1590) and Abs (2242) are absorbance peaks recorded at 1590 cm −1 and 2242 cm −1 , which correspond to C═N groups and nitrile (—CN) groups, respectively; and
exposing the pre-stabilised precursor to an oxygen containing atmosphere at a temperature in a range of from 200° C. to 300° C. to form the stabilised precursor;
wherein prior to the pre-stabilised precursor being exposed to the oxygen containing atmosphere it is cooled to a temperature below the temperature of the oxygen containing atmosphere.
2. The process according to claim 1 , wherein the precursor is heated in the substantially oxygen-free atmosphere for period of no more than about 5 minutes.
3. The process according to claim 1 , wherein the amount of tension applied to the precursor is selected to promote formation of at least 15% cyclised nitrile groups in the pre-stabilised precursor as determined by Fourier transform infrared (FT-IR) spectroscopy using the equation defined in claim 1 .
4. The process according to claim 1 , wherein the amount of tension applied to the precursor is selected to promote maximum nitrile group cyclisation in the pre-stabilised precursor.
5. The process according to claim 1 , wherein the pre-stabilised precursor is exposed to the oxygen containing atmosphere for a time period of no more than about 20 minutes.
6. The process according to claim 1 , wherein the pre-stabilised precursor is heated in the oxygen containing atmosphere at a temperature that is lower than that used for forming the pre-stabilised precursor.
7. The process according to claim 1 which is a continuous process.
8. The process according to claim 1 , further comprising a step of determining a tension parameter for a precursor prior to forming the pre-stabilised precursor, wherein determining the tension parameter for the precursor comprises:
(a) selecting a temperature in a range of from 250° C. to 400° C. and time period for heating a precursor in a substantially oxygen-free atmosphere containing not more than 0.005% by volume of an oxygen containing molecule;
(b) applying a range of different substantially constant amounts of tension that vary by less than 5% to the precursor while heating the precursor in the substantially oxygen-free atmosphere at the selected temperature and for the selected time period;
(c) determining by Fourier transform infrared (FT-IR) spectroscopy using the equation defined in claim 1 the amount of cyclised nitrile groups (EOR (%)) formed in the precursor for each substantially constant amount of tension applied to the precursor;
(d) calculating a trend of extent of nitrile group cyclisation versus tension,
(e) identifying from the calculated trend the amounts of tension providing at least 10% nitrile group cyclisation and maximum nitrile group cyclisation; and
(f) selecting an amount of tension giving rise to at least 10% nitrile group cyclisation to pre-stabilise the precursor.
9. A process for preparing a carbon fibre comprising the steps of:
providing a stabilised precursor fibre prepared according to a process comprising
heating a precursor comprising polyacrylonitrile at a temperature in a range of from 250° C. to 400° C. in a substantially oxygen-free atmosphere containing not more than 0.005% by volume of an oxygen containing molecule while applying a substantially constant amount of tension that varies by less than 5% to the precursor to promote cyclisation of nitrile groups in the precursor, the temperature and time period in which the precursor is heated in the substantially oxygen-free atmosphere and the amount of tension applied to the precursor each being selected to form a pre-stabilised precursor having at least 10% cyclised nitrile groups (EOR (%)) as determined by Fourier transform infrared (FT-IR) spectroscopy using the following equation:
EOR
(
%
)
=
(
100
×
0.29
×
Abs
(
1590
)
)
(
(
Abs
(
2242
)
+
(
0.29
×
Abs
(
1590
)
)
where Abs (1590) and Abs (2242) are absorbance peaks recorded at 1590 cm −1 and 2242 cm −1 , which correspond to C═N groups and nitrile (—CN) groups, respectively; and
exposing the pre-stabilised precursor to an oxygen containing atmosphere at a temperature in a range of from 200° C. to 300° C. to form the stabilised precursor in a time period of no more than 25 minutes, wherein prior to the pre-stabilised precursor being exposed to the oxygen containing atmosphere it is cooled to a temperature below the temperature of the oxygen containing atmosphere; and
carbonising the stabilised precursor fibre to form the carbon fibre.
10. The process according to claim 9 , wherein carbonising the stabilised precursor comprises heating the stabilised precursor in an inert atmosphere at a temperature in a range of from about 350° C. to 3000° C.
11. The process according to claim 9 , wherein the carbon fibre is formed in a time period of no more than about 45 minutes.
12. The process according to claim 9 which is continuous and comprises the steps of:
(a) feeding a precursor comprising polyacrylonitrile in to a pre-stabilisation reactor comprising a substantially oxygen-free atmosphere containing not more than 0.005% by volume of an oxygen containing molecule and heating the precursor at a temperature in a range of rom 250° C. to 400° C. in the substantially oxygen-free atmosphere while applying a substantially constant amount of tension that varies by less than 5% to the precursor to promote cyclisation of nitrile groups in the precursor, the temperature and time period in which the precursor is heated in the substantially oxygen-free atmosphere and the amount of tension applied to the precursor each being selected to form a pre-stabilised precursor comprising at least 10% cyclised nitrile groups as determined by Fourier transform infrared (FT-IR) spectroscopy using the following equation:
EOR
(
%
)
=
(
100
×
0.29
×
Abs
(
1590
)
)
(
(
Abs
(
2242
)
+
(
0.29
×
Abs
(
1590
)
)
where Abs (1590) and Abs (2242) are absorbance peaks recorded at 1590 cm −1 and 2242 cm −1 , which correspond to C═N groups and nitrile (—CN) groups, respectively;
(b) cooling the pre-stabilised precursor prior to it being exposed to an oxygen containing atmosphere and feeding it into an oxidation reactor;
(c) feeding the pre-stabilised precursor in to an the oxidation reactor comprising an oxygen containing atmosphere at a temperature in a range of from 200° C. to 300° C. and exposing the pre-stabilised precursor to the oxygen containing atmosphere to form a stabilised precursor in a time period of no more than 25 minutes; and
(d) feeding the stabilised precursor in to a carbonisation unit and carbonising the stabilised precursor in the carbonisation unit to form the carbon fibre.Cited by (0)
No later patents cite this yet.
References (0)
No backward citations on record.